engine MERCEDES-BENZ C320 2004 W203 Manual Online

276 Practical hintsWhat to do if …Problem
Possible cause
Suggested solution
?
The yellow “CHECK ENGINE”
malfunction indicator lamp
comes on while driving.
There is a malfunction in:

The fuel management system


The ignition system


The emission control system


Systems which affect emissions
Such malfunctions may result in excessive
emissions values and may switch the engine
to its limp-home (emergency operation)
mode.

Have the vehicle checked as soon as
possible by an authorized
Mercedes-Benz Center.
An on-board diagnostic connector is
used by the service station to link the
vehicle to the shop diagnostics sys-
tem. It allows the accurate identifica-
tion of system malfunctions through
the readout of diagnostic trouble
codes. It is located in the front left
area of the footwell next to the
parking brake pedal.
The fuel cap is not closed tight.

Check the fuel cap.
Your gas tank is empty.

After refuelling start the engine three
or four times in succession.
The limp-home mode is canceled. You do
not need to have your vehicle checked.

278 Practical hintsWhat to do if …Problem
Possible cause
Suggested solution
The yellow fuel tank reserve warning lamp comes
on while driving.
The fuel level has gone below the reserve
mark.

Refuel at the next gas station
(page 249).
<
The red seat belt non-usage warning
lamp illuminates for a brief period
after starting the engine.
The warning lamp reminds you to fasten
seat belts.

Fasten your seat belt.
1
The red SRS indicator lamp comes on
while driving.
There is a malfunction in the restraint sys-
tems. The airbags or emergency tensioning
device (ETDs) could deploy unexpectedly
or fail to activate in an accident.

Drive with added caution to the
nearest authorized Mercedes-Benz
Center.
Warning!
G
In the event a malfunction of the SRS is
indicated as outlined above, the SRS may
not be operational. For your safety, we
strongly recommend that you visit an autho-
rized Mercedes-Benz Center immediately to
have the system checked; otherwise the
SRS may not be activated when needed in
an accident, which could result in serious or
fatal injury, or it might deploy unexpectedly
and unnecessarily which could result in an
accident and/or injury to you or to others.

282 Practical hintsWhat to do if …Display message
Possible cause
Possible solution
ESP
ESP
NOT AVAILABLE!
The ESP was deactivated because of a
malfunction or interrupted power supply.
The ABS might not be operational.

Synchronize the ESP. With vehicle
stationary and the engine running, turn
the steering wheel completely to the
left and then to the right to synchro-
nize the ESP.
If the ESP message does not go out:

Continue driving with added caution.

Visit an authorized Mercedes-Benz
Center as soon as possible.
Failure to follow these instructions
increases the risk of an accident.
The self-diagnosis has not been
completed.
The display will clear after driving a short
distance at more than 12 mph (20 km/h).
!When synchronizing the ESP, make
sure you can turn the steering wheel in
both directions as far as it will go
without the wheels hitting any objects,
e.g. a road curb.

285 Practical hints
What to do if …
Display symbol
Display message
Possible cause
Possible solution
#
BATTERY/ALTERNATOR
VISIT WORKSHOP!
The battery was charged with a battery
charger or jump started.

Have the battery checked at a service
station.
The battery is no longer charging.
Possible causes:

alternator malfunctioning


broken poly-V-belt

Stop immediately and check the
poly-V-belt.
If it is broken:

Do not continue to drive. Otherwise
the engine will overheat due to an
inoperative water pump which may
result in damage to the engine. Notify
an authorized Mercedes-Benz Center.
If it is intact:

Drive immediately to the nearest
authorized Mercedes-Benz Center.
UNDERVOLTAGE
ENGINE ON!
The battery has insufficient voltage and
can no longer supply the convenience
functions such as seat heater*.

Start the engine (
page 43).
UNDERVOLTAGE
SWITCH CONSUMERS OFF!
The battery is malfunctioning.

Have the battery checked at a service
station.

286 Practical hintsWhat to do if …Display symbol
Display message
Possible cause
Possible solution
!
(Canada only)
;
(USA only)
PARK. BRAKE
RELEASE BRAKE!
You are driving with the parking brake
set.

Release the parking brake
(page 45).
2
BRAKE WEAR
VISIT WORKSHOP!
The brake pads have reached their wear
limit.

Have the brake pads replaced as soon
as possible.
3
BRAKE FLUID
VISIT WORKSHOP!
There is insufficient brake fluid in the
reservoir.

Risk of accident! Stop the vehicle and
notify an authorized Mercedes-Benz
Center. Do not add brake fluid! This
will not solve the problem.
Warning!
G
Driving with this message displayed can
result in an accident. Have your brake
system checked immediately. Do not add
brake fluid before checking the brake
system. Overfilling the brake fluid reservoir
can result in spilling brake fluid on hot
engine parts and the brake fluid catching
fire. You can be seriously burned.
!If you find that the brake fluid in the
brake fluid reservoir has fallen to the
minimum mark or below, have the
brake system checked for brake pad
thickness and leaks.
!Brake pad thickness must be visually
checked by a qualified technician at the
intervals specified in the Service
booklet.

287 Practical hints
What to do if …
Display symbol
Display message
Possible cause
Possible solution
B
COOLANT
CHECK LEVEL!
The coolant level is too low.

Add coolant (
page 257).

If you have to add coolant frequently,
have the cooling system checked by
an authorized Mercedes-Benz Center.
Warning!
G
Do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts. You can be seriously burned.
!Do not ignore the low engine coolant
level warning. Extended driving with
the message and symbol displayed
may cause serious engine damage not
covered by the Mercedes-Benz Limited
Warranty.
Do not drive without sufficient amount
of coolant in the cooling system. The
engine will overheat causing major
engine damage.

288 Practical hintsWhat to do if …
During severe operating conditions and
stop-and-go city traffic, the coolant tem-
perature may rise close to 248°F (120°C).
Display symbol
Display message
Possible cause
Possible solution
Ï
COOLANT
STOP, ENGINE OFF!
The coolant is too hot.

Stop the vehicle and turn off the
engine.

Only start the engine again after the
message disappears. You could
otherwise damage the engine.
Warning!
G
Driving when your engine is badly over-
heated can cause some fluids which may
have leaked into the engine compartment to
catch fire. You could be seriously burned.
Steam from an overheated engine can cause
serious burns and can occur just by opening
the hood. Stay away from the engine if you
see or hear steam coming from it.
Turn off the engine, get out of the vehicle
and do not stand near the vehicle until the
engine has cooled down.
!The engine should not be operated with
the coolant temperature above 248°F
(120°C). Doing so may cause serious
engine damage which is not covered by
the Mercedes-Benz Limited Warranty.

289 Practical hints
What to do if …
Display symbol
Display message
Possible cause
Possible solution
Ï
COOLANT
STOP, ENGINE OFF!
The poly-V-belt could be broken.

Stop immediately and check the
poly-V-belt.
If it is broken:

Do not continue to drive. Otherwise
the engine will overheat due to an
inoperative water pump which may
result in damage to the engine. Notify
an authorized Mercedes-Benz Center.
If it is intact:

Do not continue to drive the vehicle
with this message displayed. Doing so
could result in serious engine damage
that is not covered by the
Mercedes-Benz Limited Warranty.
COOLANT
VISIT WORKSHOP!
The cooling fan for the coolant is
malfunctioning.

Observe the coolant temperature
display.

Have the fan replaced as soon as
possible.

291 Practical hints
What to do if …
Display symbol
Display messages
Possible cause
Suggested solution
:
USA only:ADD 1.0 Qt. ENGINE OIL
WHEN NEXT REFUELING!Canada only:ADD 1.0 LITER ENG. OIL
WHEN NEXT REFUELING!
The engine oil level is too low.

Add engine oil (
page 255) and check
the engine oil level (
page 254).
ENGINE OIL LEVEL
STOP, ENGINE OFF!
There is no oil in the engine. There is a
danger of engine damage.

Carefully bring the vehicle to a halt as
soon as possible.

Turn off the engine.

Add engine oil (
page 255) and check
the engine oil level (
page 254).
ENGINE OIL LEVEL
REDUCE OIL LEVEL
You have added too much engine oil.
There is a risk of damaging the engine or
the catalytic converter.

Have oil siphoned or drained off.
Observe all legal requirements with
respect to its disposal.
ENGINE OIL
VISIT WORKSHOP!
It may be that there is water in the engine
oil.

Have the engine oil checked.

292 Practical hintsWhat to do if …When the message
ADD 1.0 Qt. ENGINE
OIL WHEN NEXT REFUELING!
(Canada:
1.0 LITER
) appears while the engine is
running and at operating temperature, the
engine oil level has dropped to
approximately the minimum level.When this occurs, the warning will first
come on intermittently and then stay on if
the oil level drops further.
Visually check for oil leaks. If no obvious oil
leaks are noted, drive to the nearest
service station where the engine oil should
be topped to the required level with an
approved oil.
Display symbol
Display messages
Possible cause
Suggested solution
:
ENGINE OIL LEVEL
VISIT WORKSHOP!
The engine oil has dropped to a critical
level.

Check the engine oil level
(page 254) and add oil as required
(page 255).

If you must add engine oil frequently,
have the engine checked for possible
leaks.
ENGINE OIL SENSOR
VISIT WORKSHOP!
The measuring system is malfunctioning.

Have the measuring system checked
by an authorized Mercedes-Benz
Center.!The engine oil level warnings should
not be ignored. Extended driving with
the symbol displayed could result in
serious engine damage that is not
covered by the Mercedes-Benz Limited
Warranty.